This invention relates generally to improved puffed food starch products made from cereal grains or other food starches, forming such products into various shapes, and the methods for their manufacture. More particularly, the present invention relates to puffed-rice snacks with improved crispiness, and appealing visual and physical texture, and processes of preparing such snacks.
Snacks have long been a household staple around the world and range from treats to dietary supplements. However, not too long ago a nutrition trend found chocolates, candies, ice cream, and other naturally and artificially sweetened confections, as well as potato chips, pretzels, corn chips, and the like, being replaced by more healthy products. The terms xe2x80x9clow fat,xe2x80x9d xe2x80x9cno-fat,xe2x80x9d and xe2x80x9clightxe2x80x9d have become the watch words of the health conscious in the ""90s. The trend has seen the popularity of puffed snacks, sometimes referred to as popped grain snacks and especially those made of corn and rice, steadily climb.
Very successful products have been made in the form of cakes generally made of puffed corn or rice. While these products had a heretofore acceptable amount of crispiness, they suffered from an unpleasant texture, usually nearest the core of the cake, resulting in the product sticking in teeth. The products are hockey puck-shaped (uniform in all three dimensions) and lack the appealing visual texture of conventional snack foods. The size of these snack cakes is also relatively large in size (approximately a three to four-inch disk-shaped cake). This size, as a single portion, can lead to a substantial amount of waste for some consumers, especially children. To address the problem of waste, a xe2x80x9cmini-cake,xe2x80x9d or smaller version of the original cake (about a one to two-inch disk-shaped cake or cracker) was introduced. The problems of texture and appearance, however, remained.
Examples of methods for making conventional grain cake products are disclosed in the described methods of U.S. Pat. No. 4,888,180 to Wu. These cake-forming devices are most frequently used with rice as the cereal grain since rice is capable of relatively easy expansion into a self-supporting cake. Statistics show that the availability and versatility of rice have not only made it an industry favorite, but a consumer favorite as well. The annual world rice harvest in the early 1990s exceeded 510 million metric tons, an increase of about 30 percent over the average during the period from 1979 to 1981. Rice grains are extensively used as human food, constituting the principal food of almost one-half the human race. The leading rice producers are China, with 36 percent of world output in the early 1990s, and India, with 22 percent. In the United States, production averaged close to 7 million metric tons, with Arkansas, California, Louisiana, and Texas being the leading rice-producing states.
Rice puffing and, in general, cereal puffing (or cereal popping) methods are well established in the prior art. Generally, methods known in the art rely primarily on a moisture content in the grains for puffing. The moisture content can be varied by many processes, such as, drying, cooking, parboiling, and tempering. Examples of attempted improvements in processing methods are described in U.S. Pat. Nos. 4,281,593 to Gevaert, 4,328,741 to Yoshikazu, and 4,667,588 to Hayashi.
There are two generally practiced methods for expanding or puffing grains: (1) heating the kernels of grain until they become extensible (i.e. until the starch becomes amorphous or flowable) at which point further heating permits evaporation of moisture (and out-gassing of some minor amounts of other gases entrained in the grain) which causes expansion (bubble formation) in the amorphous starch; (2) heating the grain kernels to a flowable state at atmospheric pressure, then suddenly reducing the pressure (partial vacuum) again permitting enhanced vaporization and out-gassing, and again causing expansion (bubble formation) in the amorphous starch; and (3) heating the grain kernels to a flowable state in a chamber where pressure is permitted (or caused) to build, then suddenly reducing the pressure to atmospheric, permitting enhanced vaporization and out-gassing and again causing expansion (bubble formation) in the amorphous starch.
This latter method is most conventionally used to make rice cakes of both the larger and xe2x80x9cminixe2x80x9d sizes. This latter method is carried out in what is commonly referred to as rice popping machines. These machines provide a chamber defined by heated chamber walls. Once the pre-puffed grain is placed in the chamber, it is closed to a pressure seal. The food starch is heated by contact with the chamber walls. The amount of food starch, i.e. the amount of grain kernels loaded into the chamber, relative to the volume of the chamber, and amount of expansion, cause the puffed product to generally conform in all three dimensions to the shape of the chamber.
One problem with conventional rice popping processes is that the filling of the entire volume of the popping chamber upon expansion may limit the bubble size formed, or full expansion of the bulk amount of the food starch, or both. This may account for a less than fully crisped product and a teeth-sticking texture of the resulting rice cake. It is certainly responsible for the hockey puck-shape of the product, which heretofore was thought to be desirable.
Another problem which exists in use of rice popping equipment is trying to balance providing sufficient time to present good conditions for full expansion of the food starch, while at the same time trying to minimize chamber residence time to achieve high production rates. To date, this balance has produced the conventional rice cakes discussed above.
It is well known that the degree and ease of puffing is affected by many factors such as: the type of grain, the type of preprocessing (e.g. milling), the condition of the grain (e.g. moisture content), and the type of starch contained in the grain. Another advancement in puffing food starch is to puff food starch which has been floured, and to extrude it into a discrete size and shape. Such extruded pieces are cooled and dried to a state of desired moisture content and hardness for acceptable handling and storage. To date, such puffing has been limited to oven puffing or deep frying. The resulting products, however, are relatively uniform throughout the snack piece, and provide a monolithic texture to the mouth when eating them. The same can be said for the products made from the more conventional process of extrusion puffing.
The inventor is unaware of a cake-type product ever being attempted using such pelletized stock. Further, it appears that prior to the present invention, it has never been contemplated to employ such a pelletized pre-product in a rice popping machine or related process.
In sum, despite the improvements being made in the field of making puffed snack cakes from food starches, in particular rice grain, insufficient attention has been given to improving the overall visual and physical texture (e.g. crispiness) and appearance of the product. The present invention addresses these issues as well as solving the problems discussed above and providing other advantages which will become apparent to those skilled in the art upon reading the accompanying specification and claims.
The present invention provides puffed food starch snacks having an improved crispy texture and a more aesthetic appearance and methods for preparing them.
In general terms, the products are snack chips, cakes, crackers or the like, made from food starch. Preferably, the starch material is provided primarily in the form of individual kernels or pellets of a cereal grain, such as rice, corn, wheat, rye, oats, millet, sorghum, barley, buckwheat, or mixtures thereof. Quantities of other food starches may also be employed as a co-mixed constituent, or as the primary source of bulk starch material, for example, potato starch. A quantity of the food starch is puffed (expanded) in a manner which forms a snack product of considerable crispiness, lightness, and unique texture to both the mouth and eye.
According to one aspect of the invention, a puffed snack product comprises a puffed starch body having a generally regular perimetrical shape, and opposed upper and lower surfaces. At least one of the upper and lower surfaces has a substantially wavy contour such that it appears as though individual kernels of grain are joined to one another. It is preferred that the substantially wavy surface of the starch body comprises hills and valleys, noted by the rise and fall of the surface along a parallel plane.
In a preferred embodiment, the puffed snack product is comprised primarily of rice starch, but may further include puffed corn starch, puffed wheat starch, puffed potato starch, or the like.
In other presently preferred embodiments, the puffed snack product may be comprised primarily or predominantly of puffed corn starch, puffed wheat starch, or puffed potato starch, with combinations of other such grains possible. Presently, a preferred perimetrical shape of the food product is generally circular, hence a rounded cake in two dimensions. Alternatively, other embodiments may include a perimetrical shape which is generally triangular, square, rectangular, or any other such geometric or fanciful shape as may be thought at the time to have consumer appeal or processing, handling, or packaging advantages.
According to another aspect of the invention, the bulk cake product is comprised of an amount of food starch in the form of a plurality of individual whole kernels of grain, puffed together. At least a portion of these whole kernels may be rice kernels, wheat kernels, or both, and may additionally include corn grits.
According to another aspect of the invention, the cake or snack body is formed from a bulk amount of food starch comprised of a plurality of individual pellets (formed from starchy flour) all puffed together. Such pellets are preferably made from rice flour, wheat flour, corn flour, potato flour or the like, and may additionally include corn grits. A sufficient amount of pellets (and corn grits, if desired) capable of becoming amorphous in the puffing chamber should be provided, such that all of the pellets and grits touch at least one other pellet or grit after becoming amorphous.
According to another aspect of the invention, a puffing chamber is provided having inner surfaces and a chamber volume. A bulk amount of the food starch is placed into the puffing chamber. The bulk amount of food starch material is caused to volumetrically expand. The expanding food starch is constrained in its expansion in at least a first dimension, while permitting expansion of the bulk amount in at least a second dimension.
The step of constraining expansion may additionally include constraining expansion of the bulk amount in a third dimension. The constraining may achieve a defining of the general shape of the final product in the first dimension, or in both the first and third dimensions. The defined shape may be provided by, in one particular embodiment, constraining expansion with certain of the inner surfaces of the puffing chamber. Preferably, for the snack cake disclosed in the example below, the unconstrained second dimension is height.
Another method of the present invention includes predetermining the bulk amount of food starch material to be placed into the chamber. The predetermining should provide a sufficient amount of whole kernels (or corn grits, if desired) capable of becoming amorphous, such that all of the kernels or grits touch at least one other kernel or grit after becoming amorphous.
Where pellets are used, the method may further include forming the pellets generally to the size of a whole kernel of grain selected from the group of grains including rice, wheat, barley, oats, rye, and corn.
Another aspect of the invention provides for puffing a food starch capable of becoming amorphous into a food starch product, wherein the food starch is first floured then pre-gelatinized in an extruder under a pressure and temperature. The food starch is then extruded and cut into pellets. The pelletized food starch is placed into a puffing chamber where increasing the pressure and the temperature in the chamber causes the pelletized food starch to become amorphous. By quickly reducing the pressure in the chamber, the amorphous starch pellets expand.
The pellets are believed to provide superior puffing (at least relative to a given time and temperature cycle in mass production) to whole kernels. While presently unproven, the advantages are believed to be that: (1) the pellets are pre-gelatinized and may allow more of the heat energy (in the given cycle time or amount of thermal energy) to contribute to water vaporization and bubble formation (as opposed to providing energy to accomplish a greater crystalline phase change) than in a grain kernel; (2) the pelletized rice has been pre-floured, hence the mechanical and physical boundaries of the cellular structure have already been broken down leading to a more uniform expansion with less (heat) energy required to break down the cellular structure; and (3) the uniform pellet structure has a more uniform distribution of both starch and moisture for improved crisp puffing.
According to another aspect of the invention, the extruded food starch pellets may be cooled under sufficiently controlled (slowly) parameters to reduce stress in the pellet (i.e. an annealing of the pellets). This should reduce the energy required for possible annealing in the popping chamber. Also, the slow drying should enhance endurance of further handling without fracturing. The extruded pellets should be provided with sufficient drying to enhance shelf life and to prevent pellets from sticking together in storage.
It is also possible that, once gelatinized, the pellets are cooled in such a way as to reduce recrystallization of the starch. This may also assist in puffing in that for a fixed amount of energy input, energy is not wasted unduly on annealing in the puffing chamber. However, such a cooling may be at odds with the slow cooling for stress reduction. While one type of cooling may be used as a trade off for the other, stress reduction presently looks to be the preferred goal.